Malagasy mountain mouse

A specimen was captured in 1929 during the Mission Zoologique Franco-Anglo-Américaine to Madagascar, but the rodents obtained by the expedition were never studied in detail. It was not until the 1970s that Karl Koopman and Guy Musser recognized that the animal—whose skin had landed at the American Museum of Natural History in New York, while the skull was at the Muséum national d'histoire naturelle in Paris—represented an otherwise unknown species. However, they never published their results. In 1993, Steven Goodman rediscovered the species on Madagascar and in 1996 he and Michael Carleton finally published a formal description. They named the animal Monticolomys koopmani, as the sole member of a new genus. The generic name Monticolomys means "mountain-dwelling mouse" and refers to the animal's montane habitat, and the specific name koopmani honors Karl Koopman for his many contributions to mammalian systematics. Common names in use for the animal also include "Koopman's montane voalavo" and "Malagasy mountain mouse". Monticolomys, however, does not follow this pattern, in that it is similar and closely related to the gerbil-like genus Macrotarsomys of western Madagascar. This relationship was originally proposed by Goodman and Carleton based on morphology, and was strongly supported by a DNA sequence analysis (based on the cytochrome b gene) published in 1999. While this study provided some weak support for a relationship between the Macrotarsomys–Monticolomys clade and the giant jumping rat, Hypogeomys, a later study based on the IRBP gene instead placed Macrotarsomys–Monticolomys sister to a clade containing four other nesomyine genera—Eliurus, Voalavo, Gymnuromys, and Brachytarsomys. ==Description==

The Malagasy mountain mouse is a small, mouse-like rodent, and quite different in appearance from most other nesomyines. It has a thick, soft fur, which appears dark brown on the upperparts. The cover hairs (which comprise most of the fur) are tricolored: for the basal two-thirds of their length, they are plumbeous gray; the middle is ochraceous; and the tip is dark brown to black. The longer guard hairs, which are most common towards the middle of the back, are completely black. The fur of the underparts appears dark gray and is not sharply demarcated from the upperparts. There, the hairs are also plumbeous at the bases, but the tips range from white to yellowish-brown. The mystacial vibrissae—whiskers above the mouth—are medium-sized. The short, rounded ears are densely covered with grayish hairs. There are white hairs on the upper sides of the metapodials and digits, and long ungual tufts—tufts of hair surrounding the bases of the claws—are present. The thumb of the forefeet bears a nail, but claws are present on the other digits. is covered with small scales and light brown hairs. Head and body length is , tail length is , hindfoot length is , ear length is , and body mass is . The skull is small and delicate. The front part, the rostrum, is narrow and relatively long. The nasal bones are rounded at the front, but blunt at the back. The zygomatic plate—a bony plate at the side of the skull—is narrow and extends back to the front margin of the first upper molar (M1). The incisive foramina, openings in the front part of the palate, extend back to a point between the front roots of the M1s. The bony palate itself is broad and lacks many indentations and protuberances present in other species. Its posterior margin is at the level of the upper third molars (M3s). There is no alisphenoid strut, so that the masticatory-buccinator foramen and the foramen ovale accessorium, two openings on the underside of the skull, are fused. The upper incisors have orange enamel and are opisthodont, with the cutting edge of the tooth inclined backwards. The root of the lower incisors extends though the mandible (lower jaw) to a low capsular process at the back of the jawbone. The molars are brachyodont (low-crowned) and bear distinct cusps. The second molars, although decidedly smaller than the first, are similar in their crown morphology, but the much smaller third molars are reduced and more distinct from the first molars in morphology. The molars are quite similar to those of Macrotarsomys, and differ only in minor details. ==Distribution and ecology==

The species' range is now known to extend across the mountain ranges of eastern Madagascar from the Tsaratanana Massif south to Andohahela, at above sea level. It occurs in montane forest, but also in degraded grassland, At Ankaratra, where the species was recorded in 1929, it occurred in such grassland, where the nesomyine Brachyuromys betsileoensis was also found. At Andringitra, the animal was recorded in high montane forest together with six other nesomyines—Brachyuromys ramirohitra, Eliurus minor, Eliurus tanala, Eliurus webbi, Gymnuromys roberti, and Nesomys rufus—as well as the black rat. At Andohahela, Monticolomys was found at an altitude of in sclerophyllous forest. Its distribution corresponds to the High Mountain Domain, a region defined on the basis of plant distributions. This region is now discontinuous, but the High Mountain Domain habitat was continuous from mountain to mountain as recently as the early Holocene. Subfossil remains have been found in Mahajanga Province (northwestern Madagascar). Malagasy mountain mouse is morphologically uniform across its wide distribution. The Malagasy mountain mouse is nocturnal and solitary and produces litters of up to three offspring. It is scansorial, spending time on the ground but also climbing in vegetation. ==Conservation status==

As Malagasy mountain mouse is now known to be a widespread, common species occurring in at least one protected area (Andringitra National Park; it may also occur in Ankarana Special Reserve), it is listed on the IUCN Red List as "Least Concern". However, fires pose a threat in montane forest and, at lower elevations, its habitat is being converted into agricultural land. ==References==

• Carleton, M.D. and Goodman, S.M. (1996). "Systematic studies of Madagascar's endemic rodents (Muroidea: Nesomyinae): A new genus and species from the Central Highlands". Fieldiana Zoology 85:231–250 • Goodman, S.M., Rakotondravony, D., Schatz, G. and Wilmé, L. (1996). "Species richness of forest-dwelling birds, rodents and insectivores in a planted forest of native trees: a test case from the Ankaratra, Madagascar". Ecotropica 2:109–120 • Goodman, S.M., Carleton, M.D. and Pidgeon, M. (1999). "Rodents of the Réserve Naturelle Intégrale d'Andohahela, Madagascar". Fieldiana Zoology 94:217–249 • Goodman, S.M., Ganzhorn, J.U. and Rakotondravony, D. (2003). "Introduction to the mammals". pp. 1159–1186 in Goodman, S.M. and Benstead, J.P. (eds.). The Natural History of Madagascar. University of Chicago Press, 1728 pp. • Jansa, S.A., Goodman, S.M. and Tucker, P.K. (1999). "Molecular phylogeny and biogeography of the native rodents of Madagascar (Muridae: Nesomyinae): A test of the single-origin hypothesis". Cladistics 15:253–270 • Jansa, S.A. and Weksler, M. (2004). "Phylogeny of muroid rodents: relationships within and among major lineages as determined by IRBP gene sequences" Molecular Phylogenetics and Evolution 31:256–276 • • Maminirina, C.P., Goodman, S.M. and Raxworthy, C.J. (2008). "Les micro-mammifères (Mammalia, Rodentia, Afrosoricida et Soricomorpha) du massif du Tsaratanana et biogéographie des forêts de montagne de Madagascar". Zoosystema 30(3):695–721 (in French) • Mein, P., Sénégas, F., Gommery, D., Ramanivosoa, B., Randrianantenaina, H. and Kerloc'h, P. (2010). "Nouvelles espèces subfossiles de rongeurs du Nord-Ouest de Madagascar". Comptes Rendus Palevol 9(3):101–112 (in French, with abridged English version). • • Rasolonondrasana, B.P.N. and Goodman, S.M. (2006). "The influence of fire on mountain sclerophyllous forests and their small-mammal communities in Madagascar". pp. 77–87 in Spehn, E.M., Liberman, M. and Körner, C. (eds.). Land Use Change and Mountain Biodiversity. Boca Raton, Florida: CRC Press, 361 pp.